The July estimate is 15% higher than July last year, which was at £16.7bn.

It is the highest monthly figure since August 2008, when the value reached £19.3bn.

CML market and data analyst Caroline Offord said: "Mortgage activity seems to have remained robust following the regulatory changes but the eventual impact of these remains uncertain.

"Property transactions in the first half of the year showed a 25% increase compared to the same period a year ago but, as set out in our recent market forecast update, we expect that intensifying affordability pressures could start to dampen this upwards trend.

"Economic conditions have strengthened, but while the Bank of England has signalled an improved economic outlook since May, headwinds remain and the message about future rate rises being measured and gradual remains unchanged."